#include <stdio.h>
int main()
{
    int a = 10;
    int b = a++;//先赋值， 后加一

    printf("%d\n", a);
    printf("%d\n", b);

    int c = -10;
    printf("%d\n", -c);//单目运算符

    float d = (int)3.14;//强行装换
    printf("%f\n", d);
    return 0;
}